The present invention relates to a data recording medium on which optical data may be recorded, for example, by focusing a laser beam on a radiation-sensitive recording layer to form a pit in the recording layer and from which the recorded optical data may be read out.
A conventional data recording medium of this type (to be referred to as a record for brevity hereinafter) is so constructed, as shown in FIG. 1, that transparent substrates 2 each having a radiation-sensitive recording layer 1 on the opposing surface thereof are bonded to each other through spacers 4 with a space 3 formed therebetween.
With this structure, parts of the recording layers 1 are exposed to the air within the space 3. When the record is transferred from a place at high temperature and high humidity to a place at low temperature, the air in the space 3 is rapidly cooled and condensate is attached to the recording layers 1. This degrades the recording layers at an early stage and also causes the problems of drop in sensitivity, an increase in noise, and so on.